U.S. patent application number 09/893124 was filed with the patent office on 2002-01-24 for apparatus and method for the remediation of particulate material and toxic pollutants in transit in flue gas.
Invention is credited to Bergemann, Christian, Plank, Christian, Steinke, Richard A..
Application Number | 20020007731 09/893124 |
Document ID | / |
Family ID | 27223041 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020007731 |
Kind Code |
A1 |
Steinke, Richard A. ; et
al. |
January 24, 2002 |
Apparatus and method for the remediation of particulate material
and toxic pollutants in transit in flue gas
Abstract
The invention is in an apparatus for the remediation of
particulate material and gaseous pollutants from a flue gas flow
that is simple and highly efficient in removing nearly all toxic
pollutants, particularly sulfur dioxide, from a flue gas flow, and
includes a manifold that is to receive and pass a polluted flue gas
flow that mounts an injector that is fitted into the manifold wall
to inject finely ground sorbent materials counter-current to the
flue gas flow, creating turbulence and a thorough mixing to effect
compaction and/or agglomerization of the pollutant and sorbent
particles. The invention provides for a sensing of the moisture
content of the flue gas flow of the compacted and agglomorized
sorbent and pollutant particles and, as needed, as water as a fine
or atomized mist a required humidity in the combined particulates
as is suitable for particle separation in a particulate removal
system as the invention is connected to, with, when the invention
is arranged with a bag house particulate removal system, the
moisture content of the compacted flue gas and sorbent material
particles is maintained at from eighteen to twenty percent
humidity.
Inventors: |
Steinke, Richard A.;
(Boulder City, NV) ; Plank, Christian; (Seefeld,
DE) ; Bergemann, Christian; (Berlin, DE) |
Correspondence
Address: |
M. Reid Russell
1240 East 100 South, # 10
St. George
UT
84790
US
|
Family ID: |
27223041 |
Appl. No.: |
09/893124 |
Filed: |
June 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09893124 |
Jun 26, 2001 |
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09323215 |
Jun 1, 1999 |
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60214286 |
Jun 26, 2000 |
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Current U.S.
Class: |
95/10 ; 422/108;
422/111; 422/169; 422/170; 422/171; 422/172; 95/107; 95/92; 96/111;
96/134; 96/150 |
Current CPC
Class: |
C12N 15/1013 20130101;
C12N 13/00 20130101 |
Class at
Publication: |
95/10 ; 422/172;
422/169; 422/170; 422/171; 422/108; 422/111; 95/107; 95/92; 96/111;
96/134; 96/150 |
International
Class: |
B01D 053/50; B01D
053/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 26, 2000 |
EP |
00113083.0 |
Claims
I claim:
1. An apparatus for removing particulate matter and pollutants from
a gas stream comprising, a duct having a gas inlet first end
connected to receive a gas stream containing pollutant particles,
said duct defining a straight passageway between said at a first
end and a second end that connects to vent particulates into a
particulate removal means, said duct having a length and has a
sorbent material injector means fitted into a duct side at a
sorbent introduction site, with said sorbent material injector
means having a nozzle end located within the duct that is to pass
particles of a sorbent material into, and counter-current to, a
flue gas flow, passing through said duct that contains pollutant
particles, providing mixed and compacted sorbent material and
pollutant particles; a moisture sensor means installed in said duct
downstream from said injector means nozzle end to read moisture
content of the gas stream containing said mixed and compacted
sorbent material and pollutant particles; moisture injector means
fitted into said duct downstream from said moisture sensor means
and spaced from twenty to thirty feet from said sorbent material
injector means nozzle end for injecting water, as a mist, into said
gas stream containing said mixed and compacted sorbent material and
pollutant particles, which said moisture injector means is
connected to a source of water and is operated in response to a
sensing, by said moisture sensor means, of a requirement to
moisturize said gas stream containing said mixed and compacted
sorbent material and pollutant particles to provide a moisture
content thereto that is a percentage of from eighteen to twenty
percent of saturation, and which said moisture is injected into
said mixed and compacted sorbent material and pollutant particles
prior to its passage into a removal means; removal means for
removing said mixed and compacted sorbent material and pollutant
particles.
2. The apparatus as recited in claim 1, wherein the moisture
injector means that is located in the duct, twenty to thirty feet
downstream from the sorbent material delivery means, is connected
to operate on command from the moisture sensor means, to pass a
moisture flow into said duct, to provide moisture to said mixed and
compacted sorbent material and pollutant particles, downstream from
said sorbent injector means, to raise the moisture content so as to
promote reaction of said mixed and compacted sorbent material and
pollutant particles that pass into the removal means.
3. An apparatus as recited in claim 2, wherein the moisture
injector meas includes a nozzle that provides water, as a fine
water mist, into said mixed and compacted sorbent material and
pollutant particles.
4. An apparatus as recited in claim 3, wherein moisture is passed
through a nozzle end of the moisture injector means as a fine water
mist into the mixed and compacted sorbent material and pollutant
particles to provide a moisture content of from eighteen to twenty
percent of a saturation humidity.
5. An apparatus as recited in claim 4, wherein the moisture
injector means includes a nozzle end arranged to inject a mist of
water droplets that have diameters of from ten to fifteen
microns.
6. An apparatus as recited in claim 1, wherein said removal means
is a bag house system connected by a vent to the second end of the
duct passageway, and said bag house includes a plurality of bags
having open ends therethrough the mixed and compacted sorbent
material and pollutant particles are directed, and each bag is
formed from a bag material having pores that each function as a
site for receiving the mixed and compacted sorbent material and
pollutant particles.
7. An apparatus as recited in claim 1, wherein sorbent material is
selected for its reaction capability with particulate matter of the
flue gas stream and is ground to a fine consistency of from one
hundred fifty to three hundred fifty mesh.
8. An apparatus as recited in claim 1, wherein said sorbent
material is a hydrated lime, quick lime or limestone.
9. An apparatus as recited in claim 1, further including an initial
sensor means for measuring gas flow pressure and temperature that
is located in the duct upstream from the sorbent material injector
means to measure the entering flue gas stream temperature, pressure
and moisture content as are present in said flue gas stream prior
to introduction of sorbent material therein.
10. An apparatus as recited in claim 9, wherein the initial sensor
means is connected to control operation of the sorbent material
injector means to increase or decrease sorbent material volume of
flow and pressure, and to control operation of a valve that is
opened on command of said initial sensor means to pass a moisture
flow into said sorbent material passing into said sorbent material
injector means.
11. An apparatus as recited in claim 1, further including at least
one static fin or plate, secured along a coupling edge thereof to a
duct inner wall, extending from said duct inner wall toward said
duct longitudinal center axis, and slanting with the direction of
flue gas steam flow at an angle from said duct inner wall that is
less than ninety degrees.
12. An apparatus as recited in claim 1, wherein the sorbent
material injector means includes a straight tube that is fitted
through and secured at its outer surface to the duct so as to form
an angle of from thirty to sixty degrees to the duct interior wall,
sloping into the gas stream flow.
13. A method for the remediation of particulate material and gases
from a flue gas stream consisting of injecting a flow of sorbent
material particles as a counter-current flow to the flue gas stream
into a flue gas stream that contains pollutant materials and gases
creating turbulence and mixing and compacting sorbent material and
pollutant particles; measuring the moisture content of the flow of
compacted sorbent material and pollutant particles; and, as needed,
adding water as a mist to said flow of said mixed and compacted
particles so as to raise the moisture content of said flue gas
stream to a moisture content as is appropriate for a removal system
whereto said flue gas stream is directed that is selected to remove
the compacted particulates from the flue gas stream.
14. A method as recited in claim 13, wherein lime is ground to a
particle size of from fifty (50) to three hundred fifty (350) mesh
as the selected sorbent material.
15. A method as recited in claim 13, wherein the sorbent material
particles are injected into the flue gas flow at an angle of
between forty-five (45) and ninety (90) degrees counter-current to
the flue gas stream direction of flow.
16. A method as recited in claim 13, wherein the sorbent material
particles are injected through a nozzle at a pressure that is
selected to provide particle mixing and compaction while allowing
the combined flue gas stream and sorbent material flow to continue
to a particulate removal system.
17. A method as recited in claim 16, wherein the moisture content
of the combined flows is sensed before passage into the particulate
removal system and moisture is added to the combined flue gas
stream and sorbent material particles, as a fine spray, and in an
amount, as needed, to raise the flue gas stream a moisture content
so as to provide a reaction and separation of the compacted
particulates in the selected particulate removal system.
18. A method as recited in claim 17, wherein moisture is added, as
needed, to the combined flue gas stream as a fine or atomized mist
having droplets of from ten (10) to fifteen (15) microns.
19. A method as recited in claim 18, wherein where the selected
particulate removal system is a bag house system, and the moisture
as is added to the combined flue gas stream raises the moisture
content thereof to between eighteen (18) and twenty (20)
percent.
20. A method as recited in claim 19, where the bag house utilizes
polyester bags.
21. A method as recited in claim 13, further including, prior to
injection of the sorbent material particles into the flue gas flow,
sensing the flue gas temperature and moisture content and, as
needed, increasing the pressure and/or volume of the sorbent
material that are injected countercurrent into the flue gas stream;
and, as needed, adding water to said flue gas flow.
22. A method as recited in claim 13, further including interposing
one or more fins or plates into the combined sorbent material and
flue gas stream to promote additional turbulence and particle
compaction.
Description
[0001] The present application is a continuation in part
application based upon an original application Ser. No. 09/323,215,
filed Jun. 1, 1999, entitled: IMPROVED APPARATUS AND METHOD FOR THE
REMEDIATION OF PARTICULATE MATERIAL AND TOXIC POLLUTANTS
TRANSPORTED IN FLUE GAS.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to methods and apparatus for the
remediation of particulate matter and toxic flue gas pollutants in
transit in a flue gas stream, and in particular to methods and
apparatus for removal of materials and pollutants, such as sulfur
dioxide, from flue gases produced in coal fired power plants, and
the like, by forcing and promoting a reaction between the
pollutants and selected sorbent materials.
[0004] 2. Prior Art
[0005] In the combustion of fossil fuels, as for power generation,
a variety of particulate matter and gaseous pollutants, some of
which are toxic, are produced and discharged as flue gas. Among
which are oxides of sulphur, including sulphur dioxide, SO.sub.2;
oxides of nitrogen and volatile organic compounds. The oxides of
sulphur, particularly sulphur dioxide SO.sub.2, are generally
considered as the most serious and are toxic pollutants. To remove
flue gas pollutants, a number of pollution control systems have
been developed that remove fine particulate matter and submicron
size particles. Some such systems rely on electrostatically charged
sorbent particles to attract and agglomerize with unlike charged
particles in the flue gas stream, providing particles of a
sufficient size to be removed in a moving fluidized bed, by passage
through a bag house, in a centrifuge system, or the like. Examples
of several such systems that one of the present inventions is a
co-inventor of are found in U.S. Pat. Nos. 5,308,590; 5,312,598;
and 5,332,562.
[0006] Functionally and structurally distinct from such
electrostatic charging system, a system for promoting a reaction
between pollutants and sorbent material by providing compaction and
mixing of the agglomerized particles of pollutant and sorbent
materials for separation in a conventional bag house, centrifuge,
or the like, is set out in U.S. patents to one of the present
inventors, U.S. Pat. Nos. 5,723,099 and 5,795,549. The above '099
and '549 patents teach a mechanical mixing of sorbent materials
into a flue gas stream utilizing a fan or impeller, and a passing
of the mixed flow through a venturi. The present invention improves
upon these patents by providing a unique injection system for
passing a counter-current flow of sorbent materials, under
pressure, into the flue gas stream that results in a greatly
improved mixing efficiency, and which mixing continues over a long
residency period for thorough mixing and agglomerizing together of
the sorbent and pollutant particles. Further, the invention
measures and controls mix moisture content after flue gas and
sorbent mixing to, as needed, add moisture, as a fine pressurized
water spray into the flow, so as to obtain an ideal moisture
content of the agglomerized particles that makes possible the
removal of essential all the pollutant particles from the gas
stream as in a bag house, or particulate removal system.
[0007] In addition to the above cited U.S. patents to one of the
present inventors, a number of systems have been developed and
employed that provide for a remediation of toxic flue gases
utilizing sorbent material compaction, none of which, however,
anticipate the invention. For example, a U.S. Pat. No. 4,061,476 to
Holter, et al, provides for delivery of a sorbent material into a
gas stream and employs a venture that reduces the passage cross
section to stimulate mixing of a sorbent that is then reacted with
pollutants in a gas stream. The invention is, of course, distinct
from the mixing system of the '476 patent as it relies upon a
pressurized flow of sorbent materials injected into a flue gas
stream counter-current to the direction of the flue gas flow to
provide turbulence and mixing. Like the '099 and '549 patents of
one of the present inventors, the Holter, et al '476 patent, and
U.S. patents to Bortz, et al., U.S. Pat. No. 5,165,902; to Teller,
U.S. Pat. No. 4,271,134 and to Kimura, U.S. Pat. No. 4,645,653,
that is shown also in a European Patent Application, No. 0,226,863,
all involve moisturizing of the sorbent materials prior to passage
into the flue gas stream. None, however, provide for measuring the
moisture content of the mix of sorbent materials and flue gas
constituents, like the invention. Nor do they provide for adding
water thereto, as needed, to obtain an optimum moisture content of
the mix prior to separation of the agglomerized sorbent and
pollutant particles as in a bag house, or like particulate removal
system.
SUMMARY OF THE INVENTION
[0008] It is a principal object of the present invention to provide
a simple and efficient remediation apparatus and method for the
removal of flue gas pollutants that is inexpensive to produce and
maintain.
[0009] Another object of the present invention is to provide a
remediation apparatus and method that exhibits a greater efficiency
in the removal of flue gas pollutants over earlier technology.
[0010] Another object of the present invention is to provide a
remediation apparatus that includes an arrangement for thoroughly
mixing of sorbent materials into a flue gas stream by directing an
opposing flow of the sorbent materials, under pressure, a
counter-current flow into that flue gas stream and providing for an
extended residency of the particulates and sorbent materials
whereby the particles and sorbent materials join or agglomorize and
are thoroughly mixed and compacted.
[0011] Another object of the present invention is to provide a
remediation apparatus and method that provides for measuring the
humidity level or water content of the compacted sorbent materials
and flue gas pollutants and, as needed, adds water in the form of a
fine mist to the mix to maintain an optimum moisture content in the
thoroughly mixed and compacted flow of particles and sorbent
materials that will promote an efficient agglomerized particle
separation in a bag house, centrifuge, or the like.
[0012] Another object of the present invention is to provide a
remediation apparatus that can readily be retrofitted into an
existing power plant pollution removal system.
[0013] Still another object of the present invention is to provide
a remediation apparatus that is simple in its construction and has
all the component elements thereof as require periodic maintenance
and repair located outside of a flue gas flow manifold or conduit
of the invention, with feed sorbent materials and water vapor
directed into that conduit or manifold through external lines or
pipes.
[0014] Still another object of the present invention is to provide
a remediation apparatus and method that produce, as a product of
the operations thereof, a flow of agglomerized particles made up of
compacted sorbent and pollutant materials having a water content
that is optimum to facilitate their removal from the gas stream in
a bag house, centrifuge, or the like.
[0015] Still another object of the present invention is to provide
a remediation apparatus and method to produce agglomerized
particles containing compacted sorbent materials and pollution
particulates from a flue gas stream that have an optimum water
content for facilitating removal of the agglomerized particles in a
conventional bag house, allowing for a removal of nearly all
noxious pollutants from the flue gas stream.
[0016] The invention is in a new and improved apparatus and method
for the remediation of toxic pollutants in flue gases, and in
particular to a very efficient removal of sulphur dioxide
(SO.sub.2) from the flue gas as is produced by a coal burning power
plant. To provide for which pollutants removal of a large
percentage to nearly all of the noxious pollutants, in particular
sulphur dioxide (SO.sub.2), as are present in the flue gas flow, a
practice of the invention provides an enhanced mixing and
compaction of flue pollutant particles with sorbent material
particles and an extended residency together of which particles and
materials for effecting an optimal mixing and agglomerization
thereof. Whereafter, the water content of which compacted particles
is measured and enhanced, as necessary, to an optimum water content
percentage for promoting removal of the mixed and agglomerized
particulates when the flow is passed into a separation apparatus
such as a bag house, centrifuge, or the like.
[0017] A preferred embodiment of the invention includes a manifold
or tubular housing that is essentially a straight tube that is
connected into a flue gas exhaust, presenting an open flow passage
therethrough to the flue gases as are produced by a coal fired
power generation plant, or the like. An inlet nozzle connects into
the manifold at approximately a thirty (30) to sixty (60) degree
angle to the flue gas direction of flow, to pass a preferred
sorbent material, such as a finely ground lime selected from a
family including hydrated lime, quick lime, limestone, or the like,
and for some applications, may be a non-lime material such as a
phosphorus mixture, carbon compound, compound containing ammonia,
or the like, within the scope of this disclosure. The sorbent
material is passed, under pressure, through the inlet nozzle and is
injected counter-current into the flue gas flow. This sorbent
material counter-current injection and reaction chamber length
provides turbulence and an extended residency period for the
conflicting flows that produces a thorough mixing and results
essentially a total compaction of the sorbent particles with
pollutant particles in the flue gas stream, agglomerating the
particles together. Which agglomerized particles then continue
through the manifold, to the manifold exhaust end.
[0018] After mixing and compaction in the reaction chamber, the
flow is directed across a sensor that measures humidity or water
content in the mix and, as needed, adds water, in the form of a
fine mist, that is injected through a nozzle into the flow to
maintain a moisture or humidity level in the flow that is
preferably from eighteen (18) to twenty (20) percent of saturation.
In practice, finely ground sorbent particles in a range of from
fifty (50) to one hundred fifty (150) mesh are preferred where the
remediation system of the invention produces agglomerized
particulates for removal in a centrifuge type device. Whereas,
where the removal system is a conventional bag house, finer
particles are preferred of from one hundred fifty (150) to three
hundred fifty (350) mesh. While, when the invention provides
compacted materials for removal in a centrifuge system, the
moisture content passed from the remediation system of the
invention is not as critical. Where particulate removal is to take
place in a conventional bag house, the moisture content of the flow
as is passed into the bag house is critical. Accordingly, when a
bag house system, as herein illustrated, is so utilized, the
moisture content of a flow of sorbent and pollutant particles is
maintained at between eighteen (18) and twenty (20) percent and, at
this moisture content, it has been found in practice, a ninety (90)
to ninety-seven (97) and greater percent of pollutant particles,
will be removed from the flue gas flow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] These and other objects of the present invention will become
more fully apparent from the following description in which the
invention is describe in detail in conjunction with the
accompanying drawings.
[0020] FIG. 1 is a side elevation view of the improved apparatus of
the invention for the remediation of toxic flue gas pollutants
shown passing a flow of compacted and moisturized particles of
sorbent material and flue gas pollutants into a bag house, that
removes the compacted particulates from the flow;
[0021] FIG. 2 is a schematic side elevation sectional view of the
remediation apparatus of FIG. 1 shown as part of a system for the
remediation of toxic flue gas pollutants; and
[0022] FIG. 3 is a is a front sectional view of the bag house taken
along the line 3-3 of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0023] Referring now to the drawings:
[0024] FIG. 1 shows an artists depiction of a preferred form or
embodiment of the invention, as it is presently contemplated in an
improved apparatus 10, hereinafter referred to as remediation
apparatus 10, for the remediation of toxic flue gas pollutants, and
is shown aligned for passing exhaust therefrom to a bag house 11.
The exhaust, as the invention is suitable for use with, can be a
flue gas flow that originates in a plant, such as a coal fired
power plant, shown as boiler 13 in FIG. 2, that passes a flue gas
through a line 13a, shown in broken lines, and identified as arrow
A, that contains pollutants, such as sulphur dioxide (SO.sub.2).
Which pollutants are removed by the apparatus of and in a practice
of the method of the invention. show herein as a best mode. In
which practice, pollutant particulates that are compacted with fine
sorbent particles in a line section of the apparatus 10, as
discussed in detail hereinbelow, that provides for impacting flows
that create turbulence and provide for a thorough mixing during
passage therethrough, forming an agglomerized mix of particulates
are then moisturized for separation out of the flue gas flow in a
bag house, centrifuge, fluidized bed, water system, or a like
agglomerized particulate removal apparatus, for disposal.
[0025] A boiler 13 is shown in the schematic of FIG. 2 passes the
flue gas flow, arrow A, through line 13a, illustrated in broken
lines. Which flow is a waste gas as is produced from burning fossil
fuels as in a coal fired power plant, for example, with the gas
flow, arrow A, containing toxic pollutants and enters a manifold 14
of the remediation apparatus 10, shown in FIG. 1. The flow, arrow
A, includes sulfur dioxide (SO.sub.2) that must be removed before
the gas flow is vented to atmosphere. That toxic pollutant
emissions, such as those containing sulfur dioxide (SO.sub.2),
should not be vented directly into the atmosphere is without
question and, in practice, with a utilization of the apparatus 10
of the invention, ninety (90) to ninety-seven (97) and greater
percent of pollutant particles have been removed. This is in
contrast to earlier state of the art remediation systems that have,
in practice, removed up to seventy percent and usually less of
sulphur dioxide pollutant (SO.sub.2) as have been present in a
power plant flue gas, to include electrostatic charging systems,
earlier compaction systems, water scrubbers, and the like.
[0026] The invention improves upon all earlier remediation systems
and does so with a much simplified apparatus than that involved in
earlier systems and provides a simple and reliable method for its
use. Shown in FIG. 1, is an artists conception drawing of the
improved apparatus for the remediation of toxic flue gas pollutants
10 of the invention that is hereinafter referred to as remediation
system 10. The remediation system 10 is shown installed, on one
end, to line 13a from boiler 13 and on the other, to a pollutant
particulate removal facility such as a bag house facility 11,
through, it should be understood, within the scope of this
disclosure, the compacted and moisturized particulates as are
produced in the remediation system 10 of the invention can be
handled and refined from the gas flow in a number of particulate
removal facilities thjat are in addition to bag house 11, to
included, but not limited to, a centrifuge system, a moving bed
assembly, water bath system, or the like, not shown.
[0027] The apparatus of the invention provides for a compacting of,
respectively, toxic pollutant particles, here shown as sulphur
dioxide (SO.sub.2), with particles of a sorbent material that will
readily combine or agglomerated with such pollutant particles.
Specifically, in practice, lime, ground to a fine consistency has
been used as the preferred sorbent material for injection into a
flue gas flow containing sulphur dioxide (SO.sub.2) at a feed rate
of approximately 2.1 PPM lime to 1 PPM of SO.sub.2. With a use of
the remediation apparatus 10 of the invention, this operation
results in a removal of from ninety (90) to ninety-seven (97)
percent of the sulfur dioxide (SO.sub.2), when the agglomorized
flow from the remediation apparatus 10 is processed in a bag house
that receives the flue gas stream, arrow E in the Figs., as set out
below.
[0028] The above set out removal rate constitutes a very
significant improvement over operations of all other earlier
compacting and electrostatic charging systems. In practice, a
counter-current injection of the lime particulates as have been
fine ground to from fifty (50) to one hundred fifty (150) mesh and
to an even smaller mesh of approximately three hundred fifty (50)
mesh, depending upon the agglomorized particulate removal system as
is employed. In a practice of the invention lime particulates are
injected under pressure in a direction that is counter-current to
the flue gas flow. This injection, as shown in the schematic of
FIG. 2, is; preferably through an injector 15, that is shown as a
straight tube, and is fitted into a system duct or manifold 14,
that is shown as an open cylinder. The injector 15, shown as a tube
or pipe, is maintained at an angle B, that is to the manifold 14
longitudinal axis. The selected angle is preferably an angle from
thirty (30) to sixty (60) degrees that the injector 15 center
longitudinal axis makes to the outer surface of the manifold 14,
and point back into the flue gas flow, arrow A in FIG. 2. The
injector 15 provides a sorbent material flow that is directed into,
to impact and thoroughly mixed with the flow of toxic flue gas
pollutants, arrow A in FIG. 1. The manifold 14, as shown, is
preferably an open cylinder, though another appropriate shape of
tube or cylinder can be so used, within the scope of this
disclosure. So arranged, the sorbent material, that is preferably
the finely ground lime particulates selected from a family that
includes hydrated lime, quick lime, limestone, or the like.
However, for some applications that are not specifically discussed
herein, the selected sorbent material may be a non-lime material
such as a phosphorus mixture, carbon compound, a compound
containing ammonia, or the like, within the scope of this
disclosure. In practice, the selected sorbent material is injected,
under a pressure of from six (6) to ten (10) psi, as a
counter-current flow into the flue gas flow, shown as arrow A. The
selected sorbent materials are fine ground to, preferably, a size
range of from fifty (50) to one hundred fifty (150) mesh. Though,
for some applications, a preferred size of sorbent particles may be
larger or smaller within the scope of this disclosure. A flow of
sorbent materials, as shown in FIGS. 1 and 2, is gravity fed out
from a bin or hopper 16 to pass into a feeder 17 that receives
pressurized air flow that is passed thereto through a line 19 from
a pump 18, as shown in FIG. 2. Shown in FIG. 2, the pressurized air
flow with the entrained sorbent material particles is then passed,
shown as arrow C, through feed line 20 and into and through the
injector 15 feed tube. This flow, arrow C, is pressurized
appropriately to take into account the pressure of the flue gas
flow so as to create turbulence in opposing flows, so as to tumble
and thoroughly mix the sorbent material particles into, to compact
and agglomorize with, the flue gas toxic pollutant particles, in
particular sulfur dioxide (SO.sub.2). Which sorbent material
presurization is selected so as not to over-power that flue gas
flow, with the combined flows than continuing, shown as arrow D,
through the manifold 14. So arranged, the toxic pollutant and
sorbent material particulates vigorously are maintained together,
tumbling and agglomorizing together along the manifold 14 between
the injector 15 end 15b and a moisture injector 25b, as shown in
FIG. 2, and as discussed further herein. Which distance, to provide
a thorough and complete mixing is from twenty (20) to thirty (30)
feet between injector end 15b and the moisture injector. Over this
distance, the sorbent material and flue gas particles are
thoroughly mixed, the respective particles engaging one another and
are compacted and agglomerized together. Optionally, within the
scope of this disclosure and for the makeup of a particular flue
gas flow, the manifold 14 can include spaced fins 21, shown in
broken lines, that are secured along connecting edges of each to
project at an angle outwardly from the manifold 14 interior wall.
Which project angle for each fin is an angle that is less than
ninety (90) degrees to the flue gas flow. The fins 21 are provided,
as needed, to further encourage turbulence and a mixing of the
particulates in the flow. While the fins 21, for most applications,
are not needed, they are included herein as an optional
inclusion.
[0029] As set out above, the injection of the sorbent particulates
into the flue gas stream is countercurrent thereto and at a
pressure that is selected so as not to interrupt, or will create a
back pressure in, the flue gas flow, arrow A. Accordingly, as
needed, a gas flow temperature and pressure first sensor 22 can be
provided at the flue gas inlet end of the manifold 14, as shown in
FIG. 2, to sense gas flow pressure and temperature, and which first
sensor 22 is preferably also configured to read moisture content as
is present in the flue gas. Where a consistent flue gas flow
pressure is exhibited and where the flue gas water content does not
very greatly, the first sensor 22 need not be used, and while a
reading of flue gas moisture content may be desirable, for most
applications, it is not required. Where, however, such first sensor
22 is employed, it is electrically connected, shown at line 23a, to
the blower 18 to provide for controlling pressure and volume of the
sorbent materials flow that is injected into the flue gas,
illustrated by arrow A. Further, where a flue gas flow is sensed as
being dry so as to require an initial moisture addition, a water
mist can be injected into the incoming flue gas to produce a
desired moisture content to the mix of the sorbent and pollutant
particulates, as discussed hereinbelow.
[0030] To provide moisture addition to the flue gas flow into the
manifold 14, as shown in FIG. 2, the first sensor 22 is
electrically connected through a line 23b to a valve 24 to command
valve opening to pass a pressured flow of a water mist through line
29a, and into and through valve 24 and through line 19 to mix into
the sorbent material flow as is passed through line 20. The
moisturized sorbent materials flow to travel through line 20a and
into injector 15 for mixing with the sorbent material with the
combined air and sorbent material flow to pass out of the injector
15 end 15b, as a counter current flow to the flue gas flow, shown
as arrow A.
[0031] The flow of agglomerized sorbent and pollutant particulates
travel downstream from the sorbent injector 15, arrow D, for a
traveling distance D that is from twenty (20) to thirty (30) feet,
and passes across a moisture sensor 25 that extends through the
manifold 14 wall and into the flue gas flow. The distance D is the
spacing distance between the injector end 15b and the second sensor
25 that measures the moisture content of the mixed flow and, when
that moisture content is below eighteen (18) percent humidity,
passes a signal through lines 26a and 26b to command operation of
pump 27. Pump 27 provides a pressurized water flow from a reservoir
28, to operate a valve 30 located in line 29 from the water
reservoir 28 that opens to direct the flow of water through a
nozzle that produces a fine mist that is injected into the flue gas
and sorbent material mix flow, arrow E. Which moisture injection is
to elevate the moisture content to from eighteen (18) to twenty
(20) percent humidity, with the moisturized flow then traveling to
a bag house 11, like that shown in FIG. 3, wherein the agglomorized
and moisturized particles are removed from the flow, as set out and
discussed below.
[0032] In practice, water is injected through a nozzle 25b, shown
in broken lines in FIG. 2, as a fine or atomized water mist that is
distributed throughout and is thoroughly mixed into the flue gas
flow, arrow E. The mist contains droplets that range in size from
ten (10) to fifteen (15) microns, and is of a volume to achieve an
optimum flue gas mix flow humidity level that is uniform
throughout. Which humidified mix of sorbent and pollution
particulates in the flue gas flow, arrow E, is then passed into a
particulate removal facility, such as the bag house 11, of FIGS. 1
and 3, wherein the agglomerized sorbent material and pollutant
particles are removed.
[0033] In a practice of the invention, where fine sorbent material
particles are fed into the flue gas flow, arrow A, in a direction
of travel against or counter-current to that flow, intense
turbulence is created at the junction of the opposing flows,
creating a thorough mixing and over the period of residency to the
flow over the distance D, an agglomerization and compaction of the
sorbent material particles with pollutant particulates is provided
to essentially all the particles that then continue as flue gas
flow, arrow D. So arranged, particulate mixing is both thorough and
efficient, with at most few un-agglomerized particles found in the
flue gas flow, arrow D. This allows for injection of an appropriate
volume of sorbent material for the pollutant particles as are
actually present in the flue gas flow, arrow A, thereby reducing
the volume of sorbent material as is used to only the volume
actually needed to provide for a thorough and complete
remediation.
[0034] The bag house 11, as shown best in FIG. 3, is a preferred
precipitate particulate removal facility that, it should be
understood, in practice, is a standard unit that includes polyester
bags, or bags 36 that are formed to receive the flue gas and
agglomorized particulates flows therethrough and are capable of
being pulsated to shake collected particles off from the outer
surface thereof. Such bag house 11 while preferred for use with the
invention, is but one of a number of particulate removal systems as
the invention can be used with, to include a centrifuge system,
moving bed, water system, or the like, not shown. For such other
precipitate removal systems, the optimum humidity or water content
of the compacted and humidified flow, arrow F, may vary above or
below the preferred moisture content of eighteen (18) to twenty
(20) percent that is for use with a bag house 11, as set out above.
For example, in a centrifuge particulate removal system, the
particulate and water mix can be drier or very wet without a
reduction in particulate removal efficience. Such centrifuge
particulate removal systems have, in practice, provide for a
removal of from seventy (70) to seventy-five (75) percent of the
pollutant particulates from a flue gas flow that is exhausted from
the centrifuge system, not shown.
[0035] When, however, the remediation apparatus 10 of the invention
is employed with a standard bag house 11, like that shown in
schematic in FIG. 3, the agglomerized particulate removal efficient
is greatly increased to where ninety (90) to ninety-seven (97) and
greater percent of toxic pollutants, particularly sulfur dioxide
(SO.sub.2) particles are removed from the flue gas flow. This
removal efficiency is primarily do the both the long residency time
in the manifold 14, across distance D, shown in FIG. 2, that the
sorbent and toxic pollutant particles experience along with the
close control of the flue gas flow agglomorized particles moisture
content, arrow E, that enters the bag house 11. So arranged, a
maximum percentage to nearly all of the toxic pollutants,
particularly sulfur dioxide (SO.sub.2), are removed when the flow
moisture content is maintained between eighteen (18) and twenty
(20) percent.
[0036] As set out above, and the bag house 11 preferably utilizes
polyester bags 36 that are, in fact, the least expensive bags as
are used in conventional bag houses and are most effective when
used with the remediation apparatus 10 of the invention for
agglomorized particulate removal. This is apparently because the
preferred polyester bags 36 are somewhat porous and, with the flue
gas flow at the preferred moisture content, a particulate coating
is formed on the bag exterior by the entering moist particulates.
This particulate coating somewhat fills the bag pores or openings
while still allowing for a passage of the gas flow, arrow F. So
arranged, nearly all the compacted particulates are captured on the
bag surface, with the cleaned flue gas then passed out of the bag
necks 37, shown also in FIG. 1, and is vented through a bag house
housing vent stack 38, arrow F. Such venting is further encouraged
by operation of a vent fan 39 that is turned in that vent stack 38
to pull the now cleaned flue gas flow, arrow F, therethrough. In
practice, nearly all the compacted particulates, shown at 41, are
removed from the flue gas flow. Thereafter, the compacted
agglomorized particulates 41 can be removed, falling off the bag 36
outer surface, when the bag is oscillated and under the urging of
gravity. Which removed particulates 41 fall to the bottom of the
bag house housing 35 and pass out of a housing lower vent 40, shown
as a flow arrow G, to fall into a catchment vessel 42. The
collected compacted particles 41 can then be disposed of.
[0037] In a practice of the method of the invention to remove toxic
particulates, specifically sulphur dioxide (SO.sub.2) from a flue
gas flow as is produced by a coal fired power plant, a finely
ground lime is preferably used as the sorbent material and is fed
at a rate of 2.1 parts per million (PPM) of lime per 1.0 PPM of
toxic pollutant sulphur dioxide (SO.sub.2) particulates into the
flue gas flow. The finely ground lime, arrow C, is blown through an
adapter 15a located in the sorbent inlet line 15, by operation of
blower 18. Shown in FIG. 2, the lime flow passes through the nozzle
15b that is located at the end of the sorbent inlet line 15 and
enters into the flue gas flow, arrow A, counter-current to that
flue gas flow. The nozzle 15b distributes the finely ground lime
flow throughout the flue gas flow, arrow A, that continues through
manifold 14, shown as arrow B, providing a residency area across
distance D wherein a thorough mixing and efficient compaction or
agglomerization of the sorbent and pollutant particulates occurs.
Temperature and moisture content of the flue gas flow, arrow A, can
optionally, as needed, be checked at a first or initial sensor 22,
that is located in the manifold 14, upstream from the nozzle 15b
wherethrough ground lime, under pressure, is passed. The first or
initial sensor 22, when present, is connected through line 23a to
blower 18, for controlling blower operation to control sorbent
transfer, with an addition of water or moisture, when needed, is
passed through line 23b by operation of valve 24 that is also
connected to first or initial sensor 22. Which sorbent flow and
moisture additions are made to the flue gas flow to maintain a
desired pressure and moisture content, and may not, depending upon
the flue gas make-up, be required. In which case, the sensing
temperature and moisture content of the flue gas, arrow A, is not
required and first or initial sensor 22 should thereby be
considered to be optional.
[0038] The injected lime, as set out above, is preferably finely
ground to between one hundred fifty (150) to three hundred fifty
(350) mesh with, when separation of the agglomerized particles from
the flue gas flow, arrow E, is to take place in a bag house, it
must be finely ground to the smaller end of the range three hundred
fifty (350) mesh. Whereas, the lime can be ground to the larger
range of from fifty (50) to one hundred fifty (150) mesh when
another separation apparatus, such as a centrifuge system, is to be
employed. Accordingly, for a practice of the method of the
invention in the removal apparatus as the invention can be used
with, the sorbent material particulates should be of a size of from
fifty (50) to one hundred fifty (150) and up to three hundred fifty
(350) mesh.
[0039] As set out above, where the pressure and moisture content of
the flue gas flow, arrow A, are consistent, a sensing of the
moisture content and water addition is required only after the
mixing of the sorbent materials into the flue gas flow, and with
the flue gas flow containing agglomerized particulates of
pollutants and sorbent material, arrow D. To provide which sensing,
a moisture sensor 25 is, as shown in FIG. 2, positioned downstream
from where the sorbent materials are injected into the flue gas
flow and is provided to sense and command passage of water, as in a
fine mist or in atomized form, into the flue gas flow, arrow D.
Such injection is to provide a moisture content in the combined
flow of from eighteen (18) to twenty (20) percent humidity, arrow
E. This moisture content, where a bag house is to be utilized to
separate the agglomerized pollutant and sorbent particles, is
critical. Whereas, where a particle separation is performed in
other than a bag house, such as a centrifuge system, the range of
moisture content can be broader. In practice, where a particle
separation system other than a bag house is utilized, the flue gas
flow, arrow E, can have a moisture content of from twenty (20) to
twenty-five (25) percent. Which different moisture content, it
should be understood, is still within the scope of this disclosure.
To promote a thorough and uniform mixing of the injected moisture
into the flue gas flow, arrow D, the water is urged, under a
pressure of from forty (40) to sixty (60) psi, by compressed air,
out through nozzle 25a as a fine mist having a droplet size from
ten (10) to fifteen (15) microns.
[0040] As set out above, the invention provides a thorough and
complete mixing of the injected sorbent materials with toxic
pollutant particulates over the distance D. In addition to the
turbulence and mixing provided by the described counter-current
injection of the fine sorbent particles into the flue gas flow and
the long residency period of turbulence over distance D, arrow A,
further turbulence can be created with an inclusion of fins or
baffles 21 in the manifold 14 that are secured at spaced intervals
to the inner wall of the manifold, projecting into angled or
sloping in the direction os the flue gas flow. The baffles 21,
depending upon the efficiency of mixing by the counter-current
injection of the sorbent materials into flue gas flow, arrow A, and
residency period over distance D, may not be needed. If, however,
such are employed, they are preferably mounted to the manifold 14
inner wall at approximately an angle of from thirty (30) to
thirty-seven (37) degrees sloping in the direction of flue gas
flow.
[0041] While a preferred embodiment of the invention in an improved
method and apparatus for the remediation of toxic flue gas
pollutants has been shown and described herein, it should be
understood that the present disclosure is made by way of example
only and that variations to the invention as disclosed and method
are possible within the scope of this disclosure without departing
from the subject matter coming within the scope of the following
claims and a reasonable equivalency thereof, which claims I regard
as my invention.
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